devfreq: Register devfreq as a cooling device on demand

Currently the default behavior is to manually having the devfreq backend to register themselves as a devfreq cooling device.

Instead of adding the code in the drivers for the thermal cooling device registering, let's provide a flag in the devfreq's profile to tell the common devfreq code to register the newly created devfreq as a cooling device.

Suggested-by Chanwoo Choi <[email protected]>

Signed-off-by Daniel Lezcano <[email protected]>

---
V3:
- Rebased on linux-pm branch without units.h
- Set the cdev to NULL in case of error
- Added description for the cdev field in the devfreq structure
V2:
- Added is_cooling_device boolean in profile structure
- Register cooling device when the is_cooling_device boolean is set
- Remove devfreq cooling device registration in the backend drivers
V1:
- Register devfreq as a cooling device unconditionnally

---
  drivers/devfreq/devfreq.c | 13 +++++++++++++
  include/linux/devfreq.h   |  8 ++++++++
  2 files changed, 21 insertions(+)

drivers/devfreq/devfreq.c +11 -0

index bf3047896e41..cf64aeec468f 100644
@@ -11,6 +11,7 @@
  #include <linux/kmod.h>
  #include <linux/sched.h>
  #include <linux/debugfs.h>
+#include <linux/devfreq_cooling.h>
  #include <linux/errno.h>
  #include <linux/err.h>
  #include <linux/init.h>

@@ -26,6 +27,7 @@
  #include <linux/hrtimer.h>
  #include <linux/of.h>
  #include <linux/pm_qos.h>
+#include <linux/thermal.h>
  #include "governor.h"
 
  #define CREATE_TRACE_POINTS

@@ -935,6 +937,15 @@ struct devfreq *devfreq_add_device(struct device *dev,
 
  	mutex_unlock(&devfreq_list_lock);
 
+	if (devfreq->profile->is_cooling_device) {
+		devfreq->cdev = devfreq_cooling_em_register(devfreq, NULL);
+		if (IS_ERR(devfreq->cdev)) {
+			dev_info(dev, "Failed to register devfreq "
+				 "cooling device\n");
+			devfreq->cdev = NULL;
+		}
+	}
+
  	return devfreq;
 
  err_init:

drivers/devfreq/devfreq.c +1 -0

+
  	if (devfreq->governor) {
  		devfreq->governor->event_handler(devfreq,
  						 DEVFREQ_GOV_STOP, NULL);

include/linux/devfreq.h +8 -0

index 26ea0850be9b..aba7ace11b72 100644
@@ -98,11 +98,15 @@ struct devfreq_dev_status {
   * @freq_table:		Optional list of frequencies to support statistics
   *			and freq_table must be generated in ascending order.
   * @max_state:		The size of freq_table.
+ *
+ * @is_cooling_device: A self-explanatory boolean giving the device a
+ *                     cooling effect property.
   */
  struct devfreq_dev_profile {
  	unsigned long initial_freq;
  	unsigned int polling_ms;
  	enum devfreq_timer timer;
+	bool is_cooling_device;
 
  	int (*target)(struct device *dev, unsigned long *freq, u32 flags);
  	int (*get_dev_status)(struct device *dev,

@@ -156,6 +160,7 @@ struct devfreq_stats {
   * @suspend_count:	 suspend requests counter for a device.
   * @stats:	Statistics of devfreq device behavior
   * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
+ * @cdev:	Cooling device pointer if the devfreq has cooling property
   * @nb_min:		Notifier block for DEV_PM_QOS_MIN_FREQUENCY
   * @nb_max:		Notifier block for DEV_PM_QOS_MAX_FREQUENCY
   *

@@ -198,6 +203,9 @@ struct devfreq {
 
  	struct srcu_notifier_head transition_notifier_list;
 
+	/* Pointer to the cooling device if used for thermal mitigation */
+	struct thermal_cooling_device *cdev;
+
  	struct notifier_block nb_min;
  	struct notifier_block nb_max;
  };

Currently the default behavior is to manually having the devfreq backend to register themselves as a devfreq cooling device.

Instead of adding the code in the drivers for the thermal cooling device registering, let's provide a flag in the devfreq's profile to tell the common devfreq code to register the newly created devfreq as a cooling device.

Suggested-by Chanwoo Choi <[email protected]>

Signed-off-by Daniel Lezcano <[email protected]>

---
V3:
- Rebased on linux-pm branch without units.h
- Set the cdev to NULL in case of error
- Added description for the cdev field in the devfreq structure
V2:
- Added is_cooling_device boolean in profile structure
- Register cooling device when the is_cooling_device boolean is set
- Remove devfreq cooling device registration in the backend drivers
V1:
- Register devfreq as a cooling device unconditionnally

---
  drivers/devfreq/devfreq.c | 13 +++++++++++++
  include/linux/devfreq.h   |  8 ++++++++
  2 files changed, 21 insertions(+)

drivers/devfreq/devfreq.c +11 -0

index bf3047896e41..cf64aeec468f 100644
@@ -11,6 +11,7 @@
  #include <linux/kmod.h>
  #include <linux/sched.h>
  #include <linux/debugfs.h>
+#include <linux/devfreq_cooling.h>
  #include <linux/errno.h>
  #include <linux/err.h>
  #include <linux/init.h>

@@ -26,6 +27,7 @@
  #include <linux/hrtimer.h>
  #include <linux/of.h>
  #include <linux/pm_qos.h>
+#include <linux/thermal.h>
  #include "governor.h"
 
  #define CREATE_TRACE_POINTS

@@ -935,6 +937,15 @@ struct devfreq *devfreq_add_device(struct device *dev,
 
      mutex_unlock(&devfreq_list_lock);
 
+     if (devfreq->profile->is_cooling_device) {
+             devfreq->cdev = devfreq_cooling_em_register(devfreq, NULL);
+             if (IS_ERR(devfreq->cdev)) {
+                     dev_info(dev, "Failed to register devfreq "
+                              "cooling device\n");
+                     devfreq->cdev = NULL;
+             }
+     }
+
      return devfreq;
 
  err_init:

drivers/devfreq/devfreq.c +1 -0

+
      if (devfreq->governor) {
              devfreq->governor->event_handler(devfreq,
                                               DEVFREQ_GOV_STOP, NULL);

include/linux/devfreq.h +5 -0

index 26ea0850be9b..aba7ace11b72 100644
@@ -98,11 +98,15 @@ struct devfreq_dev_status {
   * @freq_table:             Optional list of frequencies to support statistics
   *                  and freq_table must be generated in ascending order.
   * @max_state:              The size of freq_table.
+ *
+ * @is_cooling_device: A self-explanatory boolean giving the device a
+ *                     cooling effect property.
   */
  struct devfreq_dev_profile {
      unsigned long initial_freq;
      unsigned int polling_ms;
      enum devfreq_timer timer;
+     bool is_cooling_device;
 
      int (*target)(struct device *dev, unsigned long *freq, u32 flags);
      int (*get_dev_status)(struct device *dev,

@@ -156,6 +160,7 @@ struct devfreq_stats {
   * @suspend_count:   suspend requests counter for a device.
   * @stats:  Statistics of devfreq device behavior
   * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
+ * @cdev:    Cooling device pointer if the devfreq has cooling property
   * @nb_min:         Notifier block for DEV_PM_QOS_MIN_FREQUENCY
   * @nb_max:         Notifier block for DEV_PM_QOS_MAX_FREQUENCY
   *

Quoted 22 lines · Daniel Lezcano

Currently the default behavior is to manually having the devfreq backend to register themselves as a devfreq cooling device.

Instead of adding the code in the drivers for the thermal cooling device registering, let's provide a flag in the devfreq's profile to tell the common devfreq code to register the newly created devfreq as a cooling device.

Suggested-by Chanwoo Choi <[email protected]>

Signed-off-by Daniel Lezcano <[email protected]>

---
V3:
- Rebased on linux-pm branch without units.h
- Set the cdev to NULL in case of error
- Added description for the cdev field in the devfreq structure
V2:
- Added is_cooling_device boolean in profile structure
- Register cooling device when the is_cooling_device boolean is set
- Remove devfreq cooling device registration in the backend drivers
V1:
- Register devfreq as a cooling device unconditionnally
---

Quoted 7 lines

      return devfreq;

err_init:

drivers/devfreq/devfreq.c +0 -0

@@ -960,6 +971,8 @@ int devfreq_remove_device(struct devfreq *devfreq)
      if (!devfreq)
              return -EINVAL;
 

drivers/devfreq/devfreq.c int devfreq_remove_device(struct devfreq *devfreq) · line 974

Quoted 1 line

drivers/devfreq/devfreq.c +1 -0

+     thermal_cooling_device_unregister(devfreq->cdev);

I have a question. Why don't you use devfreq_cooling_unregister()? When thermal_cooling_device_unregister(), how can we remove the pm_qos_request of devfreq device?

Quoted 23 lines · Chanwoo Choi

Quoted 22 lines · Daniel Lezcano

Currently the default behavior is to manually having the devfreq backend to register themselves as a devfreq cooling device.

Instead of adding the code in the drivers for the thermal cooling device registering, let's provide a flag in the devfreq's profile to tell the common devfreq code to register the newly created devfreq as a cooling device.

Suggested-by Chanwoo Choi <[email protected]>

Signed-off-by Daniel Lezcano <[email protected]>

---
V3:
- Rebased on linux-pm branch without units.h
- Set the cdev to NULL in case of error
- Added description for the cdev field in the devfreq structure
V2:
- Added is_cooling_device boolean in profile structure
- Register cooling device when the is_cooling_device boolean is set
- Remove devfreq cooling device registration in the backend drivers
V1:
- Register devfreq as a cooling device unconditionnally
---

[ ... ]

Quoted 7 lines

Quoted 7 lines

       return devfreq;

err_init:

drivers/devfreq/devfreq.c +0 -0

@@ -960,6 +971,8 @@ int devfreq_remove_device(struct devfreq *devfreq)
       if (!devfreq)
               return -EINVAL;
 

Quoted 5 lines

drivers/devfreq/devfreq.c int devfreq_remove_device(struct devfreq *devfreq) · line 974

Quoted 1 line

drivers/devfreq/devfreq.c +1 -0

+     thermal_cooling_device_unregister(devfreq->cdev);

I have a question. Why don't you use devfreq_cooling_unregister()? When thermal_cooling_device_unregister(), how can we remove the pm_qos_request of devfreq device?

You are perfectly right. I failed to call the right function :/

Will fix it with a v4.

On 21. 3. 7. 오후 11:28, Daniel Lezcano wrote:

Thanks. And, please add 'PM /' prefix for patch in order to keep the consistent patch title format.

PM / devfreq: Register devfreq as a cooling device on demand